Tech help!
TECH HELP EDITOR
Nick Fisher
Base vehicle expert
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Q Is a lithium battery compatible with my charging set-up?
I own a 2015 Roller Team 590 and the leisure battery seems to have given up; it will not hold its charge. Can I replace it with a lithium LiFePO4 battery?
I know there can be issues with charging these batteries as there is a solar panel, mains charging and charging from the engine. Can you confirm if the charging system in the ‘van is compatible or not?
Pete Gilpin
A The published ideal maximum charging regime for lithium ferrous batteries is to charge them until they reach their maximum voltage of 14.6V then switch off the charger. Most purveyors of this battery technology give a voltage tolerance of plus or minus 0.2V.
If charged up to a slightly lower voltage, the amount of charge will be slightly reduced, but the already long battery life will be extended. Most chargers can be set to a suitable voltage. Take care, however, that the charger does not have an automatic equalisation mode as this will damage a LiFePO4 battery.
A charger set to AGM mode will charge up to 14.8V, which is the very highest voltage. A charger set to wet can be 14.7V and a charger set to gel, 14.4V, which is the safest setting.
Also, the cost of LiFePO4 batteries has halved in the last couple of years, which makes them attractive regarding lightness, available depth of discharge and life cycles. Just be aware of your maximum charge or discharge currents, especially if you have a powerful inverter to power a hair dryer or microwave, as the battery management system (BMS) within the battery must be rated above your maximum currents.
Clive Mott
Q Can I isolate the vehicle’s starter battery in our Pilote P600 motorhome?
I read your reply to Ray Ryder suggesting he fit a NC (normally closed) relay to disconnect the starter battery from the Schaudt EBL unit and the leisure battery while the engine is running. The existing battery cut-out NO (normally open) relay would normally connect the starter battery to the Schaudt EBL when the engine is running. As you have wired the two sets of relay contacts in series and they are both controlled by the D+ signal, one cancels out the other, so the starter battery and Schaudt EBL are always disconnected. Surely it would be easier to just remove the 50A fuse.
In my set-up, in our 2018 Pilote P600 also fitted with a Schaudt EBL 271, I wired in the B2B, removed the 50A fuse (F2) and everything works fine. The fridge (assuming three-way) should only alarm when the engine is switched off,
